T
treez
Guest
Hello,
We have designed the attached Mains Transient imitator circuit, which exposes our LED Power supply to a synthesized “Mains Transient” voltage spike so as to see if it survives. Schem and LTspice simulation attached.
We must use IGBTs (not MOSFETs) for the switchs, since they have far better overcurrent rating, and we may see overcurrents in the event that the overvoltage spike ‘kills’ the LED power supply. :shock:
We need to be able to switch the IGBTs ON/OFF very quickly (within 1us). However, years ago, I learned that IGBTs have a large “tail current”, which means that they simply cannot be switched off quickly. We are using the STGW30NC120 IGBT (for all 4 IGBTs) , and its datasheet does not refer to this “tail current”…do you know why?...and do you believe there will be a significant “tail current”? :???:
The modus operandi of the circuit is that Switch 1 comes on first and gets the LED power supply up and running. ..Then, Switch 1 is suddenly turned OFF….and then 5us later Switch 2 is switched ON for just 100us and then suddenly switched OFF again…and then 5us later Switch 1 turns back ON again………………………………………….this is repeated continuously.
-During the short period that Switch 2 is ON, the overvoltage spike is applied to the LED power supply under test. The Overvoltage is caused by the sudden voltage step input to the LC circuit.
So what do you think about the “tail current “ problem? :???:
STGW30NC120 IGBT Datasheet:
https://www.st.com/content/ccc/reso...df/jcr:content/translations/en.CD00077681.pdf
We have designed the attached Mains Transient imitator circuit, which exposes our LED Power supply to a synthesized “Mains Transient” voltage spike so as to see if it survives. Schem and LTspice simulation attached.
We must use IGBTs (not MOSFETs) for the switchs, since they have far better overcurrent rating, and we may see overcurrents in the event that the overvoltage spike ‘kills’ the LED power supply. :shock:
We need to be able to switch the IGBTs ON/OFF very quickly (within 1us). However, years ago, I learned that IGBTs have a large “tail current”, which means that they simply cannot be switched off quickly. We are using the STGW30NC120 IGBT (for all 4 IGBTs) , and its datasheet does not refer to this “tail current”…do you know why?...and do you believe there will be a significant “tail current”? :???:
The modus operandi of the circuit is that Switch 1 comes on first and gets the LED power supply up and running. ..Then, Switch 1 is suddenly turned OFF….and then 5us later Switch 2 is switched ON for just 100us and then suddenly switched OFF again…and then 5us later Switch 1 turns back ON again………………………………………….this is repeated continuously.
-During the short period that Switch 2 is ON, the overvoltage spike is applied to the LED power supply under test. The Overvoltage is caused by the sudden voltage step input to the LC circuit.
So what do you think about the “tail current “ problem? :???:
STGW30NC120 IGBT Datasheet:
https://www.st.com/content/ccc/reso...df/jcr:content/translations/en.CD00077681.pdf